Spleen: Information, Surgery and Functions

Although most people have spleens, we don't often think about the way they function as organs in our bodies. You may have heard people use the phrase "venting spleen" – not referring to the body part itself, but as a way to describe letting out anger or frustration. The word "spleen" has come to be used metaphorically as a synonym for "anger". This is because in medieval times, the spleen was thought to be the literal, physical source of a hot temper. People thought that "venting" their spleens would remove excess anger. Fortunately, we have learned a lot since then about the spleen's purpose in our bodies.

Where is my spleen, and what does it look like?

Your spleen can be found in the upper left region of your abdomen – just behind your stomach and under your diaphragm. It is soft and purple, shaped like a very small smooth rounded catcher's mitt with notches on its upper front edge.

Size and weight can vary greatly, but the average healthy adult's spleen is about five inches long, three inches wide, and one and a half inches thick. A typical spleen weighs about six ounces when you are healthy. With some infections or other conditions, your spleen can become enlarged. When this happens, your spleen can balloon in weight to about four pounds.

This is because your spleen is highly vascular organ; it contains many vessels that carry and circulate fluids in your body. It works very closely with your blood and lymph, and can be affected by infection, malignancies, liver disease, parasites, and other conditions.

What does my spleen do?

As you've seen, your spleen is often on the "front lines" of your body; in fact, your spleen is a busy organ – especially considering its small size.

Your spleen's main function is to act as a filter for your blood. It recognizes and removes old, malformed, or damaged red blood cells. When blood flows into your spleen, your spleen performs "quality control"; your red blood cells must pass through a maze of narrow passages. Healthy blood cells simply pass through the spleen and continue to circulate throughout your bloodstream. Blood cells that can't pass the test will be broken down in your spleen by macrophages. Macrophages are large white blood cells that specialize in destroying these unhealthy red blood cells.

Always economical, your spleen saves any useful components from the old cells, such as iron. It stores iron in the form of ferritin or bilirubin, and eventually returns the iron to your bone marrow, where hemoglobin is made. Hemoglobin is an important protein in your blood that transports oxygen from your lungs to all the parts of your body that need it.

Another useful thing your spleen can do is store blood. The blood vessels in human spleens are able to get wider or narrower, depending on your body's needs. When vessels are expanded, your spleen can actually hold up to a cup of reserve blood. If for any reason you need some extra blood – for example, if trauma causes you to lose blood – your spleen can respond by releasing that reserve blood back into your system.

Your spleen also plays an important part in your immune system, which helps your body fight infection. Just as it detects faulty red blood cells, your spleen can pick out any unwelcome micro-organisms (like bacteria or viruses) in your blood.

When one of these invaders is detected in your bloodstream, your spleen, along with your lymph nodes, jumps to action and creates an army of defender cells called lymphocytes. Lymphocytes are a type of white blood cell that produces antibodies, special proteins that weaken or kill bacteria, viruses, and other organisms that cause infection. Antibodies and white blood cells also stop infections from spreading through the body by trapping germs and destroying them.

Does that mean I can't live without my spleen?

As you've seen, your spleen is a very useful organ, but it is not vital. Sometimes, a person's spleen does have to be surgically removed. This may be because the spleen becomes injured, or it may be taken out in the course of transplanting other organs.

Other parts of your body, like your lymph nodes and your liver, are able to step in and take over many of your spleen's functions. Because the spleen is so important to your immune system, people without spleens are more vulnerable to infections. This is why your doctor may tell you to take extra precautions, such as getting vaccinations, once your spleen has been removed. You will also be prescribed oral antibiotics to take daily; this is another way to prevent infection. Still, it's not uncommon to be without a spleen, and many people are able to enjoy full lives without one.